1. Field of the Invention
The invention generally relates to devices for testing the durability of elastomeric materials and more particularly to an improved testing machine for use in determining the duration of fatigue life for a plurality of elastomeric specimens simultaneously subjected to cyclic strain over a range of frequencies.
The fatigue life for elastomeric materials often is determined by employing mechanical devices which cyclically subject specimens to tensile stress, whereby failure of the stressed specimens serves to indicate the term of fatigue life for the specimens. Normally, the term of fatigue life for a specimen is dictated by factors such as test temperatures, strain amplitude and strain rate.
2. Description of the Prior Art
The prior art, of course, includes numerous devices for use in subjecting samples of elastomeric materials to destructive strain, whereby the term of fatigue life for a given elastomeric specimen is determined. However, machines currently available are economically expensive and impractical as they are incapable of use in simultaneously subjecting a plurality of specimens to strain at different strain rates and amplitudes. For example, in the aerospace industry it often becomes necessary to determine with precise accuracy the term of fatigue life for a given elastomeric material at various strain rates and amplitudes, in order to establish parameters for optimum performance and thus assure completion of a mission. As a consequence, a large number of tests are required which, in turn, requires that a large number of expensive testing machines be employed simultaneously, often for terms of impractical durations. Hence, there exists a need for a practical and economic machine adapted to be employed in determining the term of fatigue life for a plurality of elastomeric specimens simultaneously subjected to cyclic strain at selected amplitudes and strain rates varying over a desired range of frequencies.
It is, therefore, the general purpose of the instant invention to provide an improved practical and economic testing machine through the use of which the term of fatigue life for elastomeric specimens can be determined in a temperature-controlled environment, at variable amplitudes and strain rates varying over a wide frequency range.